The function of the grilling device of the conventional technique is usually single, it only can used for roast, there are also some cooking devices which has the function of both steam and roast, but most of the steam function applies ordinary steam, so the heating speed is relatively low, the heating effect by steam is not good. Chinese publication NO.CN1860972A discloses a cooking device which can used for both steam and roast, it has two heating manners including steam heating and grill heating; and Chinese publication NO.CN2815212Y discloses an electric steaming oven which has roasting function, it comprises a cooking inner chamber disposed in the oven\ a steam generator and a controlling circuit, an electric heating element for roasting is disposed in the housing; such cooking devices and so on are within the scope of the above devices.